In an upset, Tom McCarthy’s “Spotlight” won the Oscar for best picture, while Leonardo DiCaprio clinched the award for best actor in Alejandro Inarritu's “The Revenant” at the 88th Academy Awards on Sunday.

McCarthy’s film about the Boston Globe’s investigative reporting on sexual abuse by Roman Catholic priests – an ode to hard-nosed journalism – won the prize for best picture over favoured frontier epic “The Revenant”.

“This film gave a voice to survivors, and this Oscar amplifies that voice, which we hope can become a choir that will resonate all the way to the Vatican,” said producer Michael Sugar.

The surprise victory came after the well-crafted procedural, led by a strong ensemble cast, had lagged in the lead-up to the Oscars, losing ground to the flashier filmmaking of Inarritu's film.

DiCaprio won his first Oscar for best actor after four previous nominations. The 41-year-old was the clear favourite going into the awards ceremony for his grueling portrayal of a fur trapper left for dead in an icy wilderness after being mauled by a bear.

“This was an award that was a long time coming. Leonardo DiCaprio was the clear frontrunner from the moment he was nominated. When they announced his name he got a standing ovation,” FRANCE 24’s Naibe Reynoso reported from Los Angeles.

Over the course of his 25-year career, DiCaprio has matured into one of the world’s most admired and popular actors, as well as a champion of environmental causes ranging from marine reserves to the rights of indigenous people.

In his acceptance speech, DiCaprio spoke about the threat of climate change. “Let us not take this planet for granted. I do not take tonight for granted,” he said.

“Our production needed to move to the southern tip of this planet to find snow. Climate change is real, it is happening now. It is the most urgent threat facing our entire species,” he added.

Inarritu, meanwhile, took best director for a second straight year, a feat matched by only two other filmmakers: John Ford and Joseph L. Mankiewicz.

"The Revenant", which went into the ceremony with 12 nods, also won best cinematography for Emmanuel Lubezki.

‘Mad Max’ takes home most wins

George Miller's post-apocalyptic film "Mad Max: Fury Road" took home the most awards of the night, winning six Oscars in technical categories including editing, makeup, production design, sound editing, sound mixing and costume design.

Rising star Brie Larson, 26, took home the statuette for best actress for her role as an abducted young woman in indie movie “Room,” adding to her armful of trophies from other award shows.

While there were few surprises Sunday, the award for best supporting actor drew gasps. Sylvester Stallone, nominated a second time 39 years later for the role of Rocky Balboa, had been expected to win his first acting Oscar for the "Rocky" sequel "Creed." He instead lost to Mark Rylance, a famed stage actor, who co-starred in Steven Spielberg's "Bridge of Spies."

Best supporting actress went to Alicia Vikander for the transgender pioneer tale "The Danish Girl”, and the Oscar for best animated feature film went to "Inside Out", Pixar's eighth win in the category since it was created in 2001. Asif Kapadia's Amy Winehouse portrait, "Amy," took best documentary. Hungary scored its second best foreign language Oscar for Laszlo Nemes' "Son of Saul," a harrowing drama set within a concentration camp.

"Even in the darkest hours of mankind, there might be a voice within us that allows us to remain human," said Nemes. "That's the hope of this film."

Diversity controversy

But the night really belonged to host Chris Rock, whose much anticipated opening monologue left few disappointed. He confronted head-on the uproar over the lack of diversity in this year's nominees, and returned to the topic throughout the show. ("We're black," he said after a commercial break.)

"Is Hollywood racist? You're damn right it's racist," said Rock, who also sought to put the issue in perspective. "Hollywood is sorority racist. It's like: We like you Rhonda, but you're not a Kappa."

Rock had stayed quiet before the ceremony as the controversy raged over the second straight year of all-white acting nominees, leaving Hollywood and viewers eagerly awaiting his one-liners. He confessed that he deliberated over joining the Oscars boycott and bowing out as host, but concluded: "The last thing I need is to lose another job to Kevin Hart."

Aside from pleading for more opportunity for black actors, Rock also sought to add perspective to the turmoil. Rock said this year didn't differ much from Oscar history, but black people in earlier decades were "too busy being raped and lynched to worry about who won best cinematographer".

How the controversy will affect ratings for ABC is one of the night's big questions. Last year's telecast, hosted by Neil Patrick Harris, slid 16 percent to 36.6 million viewers, a six-year low.